Charge resolution in the isochronous mass spectrometry and the mass of $$^{51}$$Co

Abstract

Isochronous mass spectrometry (IMS) of heavyion storage rings is a powerful tool for the mass measurements of short-lived nuclei. In IMS experiments, masses are determined through precision measurements of the revolution times of the ions stored in the ring. However, the revolution times cannot be resolved for particles with nearly the same mass-to-charge (m/q) ratios. To overcome this limitation and to extract the accurate revolution times for such pairs of ion species with very close m/q ratios, in our early work on particle identification, we analyzed the amplitudes of the timing signals from the detector based on the emission of secondary electrons. Here, the previous data analysis method is further improved by considering the signal amplitudes, detection efficiencies, and number of stored ions in the ring. A sensitive Z-dependent parameter is introduced in the data analysis, leading to a better resolution of 34 Ar 18þ and 51 Co 27þ with A=Z ¼ 17=9. The mean revolution times of 34 Ar 18þ and 51 Co 27þ are deduced, although their time difference is merely 1.8 ps. The uncorrected, overlapped peak of these ions has a full width at half maximum of 7.7 ps. The mass excess of 51 Co was determined to be À27;332ð41Þ keV, which is in agreement with the previous value of À27;342ð48Þ keV.

Precise machine learning models for fragment production in projectile fragmentation reactions using Bayesian neural networks *

“…where , C and τ are free parameters, and minimizes odd-even staggering in the fragment distributions. This has been shown to be well obeyed by both neutron-rich [45] and neutron-deficient fragments [43,95,96], which provides an empirical approach to study the properties of recently produced neutron-deficient rare isotopes [97][98][99] and the validity of model predictions.…”

Fragmentation of stable and neutron-rich 12-16C into boron fragments at approximately 240 MeV/nucleon *

“…Our aim is to investigate the dependence of fragmentation cross sections on the isospin of a projectile, which can improve our understanding of the mechanism behind the fragmentation process. Experiments were performed at the Heavy Ion Research Facility (HIRFL) [24][25][26][27] of the Institute of Modern Physics, Chinese Academy of Sciences. An primary beam with an intensity of 10 6 particles per second was accelerated to 280 MeV/nucleon by the main Cooler Storage Ring (CSRm) synchrotron and impinged on a 15-mm-thick 9 Be production target.…”